The present invention generally relates to a recording and reproduction or retrieval system, and more particularly, to an optical signal recording and reproduction system for selective recording or reproduction of signals on a recording medium through the utilization of a laser beam.
Recently, there have been introduced, for actual applications, optical signal recording and reproduction systems enabling recording and reproduction or retrieval of video and acoustic signals to be effected with the use of laser beams, and although some of such recording and reproduction systems proposed are arranged to employ recording mediums which are composed of materials capable of erasing the recorded signals when required, most of them are not provided with functions for erasing the signals once they are recorded.
Incidentally, the optical signal recording and reproduction systems as described above are characterized in that a large capacity of information signals may be recorded therein, and are capable of accumulating information contained within papers having as many as 15,000 sheets, when such systems are applied, for example, to the filing of documents. In a case where the large capacity of information as described above is accumulated, there often arises the necessity for deleting particular portions of tracks containing, for example, information which has become useless, confidential informations, etc. Meanwhile, when the large amounts of information as stated above are accommodated, one of the requirements is that the selected information should be quickly searched for reading, and in such cases, if it is so arranged that the useless tracks which are deleted as above are rapidly identified as deleted tracks based on predetermined signals for jumping or skipping over such portions during the searching, the selected information may be conveniently read more quickly for efficient operation.
However, since most of the conventional optical signal recording and reproduction systems currently in use are incapable of erasing the previously recorded signals, they can not fully meet the requirements as described above.